Coated, molded articles, often fiber-reinforced, typically are made by spreading a gel coat composition over the surface of a mold having a surface corresponding to the article in negative relief. After cure, the gel coat composition, becomes the outermost layer of the molded article and will become exposed to the environment. The gel coat composition is spread across the mold surface by any one of a number of techniques, and usually as a relatively thick layer, e.g., up to about a 0.8 mm thick wet coating. This can help maximize weather and wear resistance, and if the molded article is fiber-reinforced, can help mask the fiber reinforcement pattern which may show through the gel coat due to inherent resin shrinkage that occurs around the fibers during cure. After the gel coat composition is applied to the mold surface, it is at least partially cured. A strengthening plastic support, optionally fiber-reinforced, is then applied behind the partially or fully cured gel coat composition using any one of a number of techniques (e.g., by brushing, hand lay-up, or spraying for open mold processes, or by casting for closed mold processes), and the resulting laminate structure is cured and demolded. Curing can be promoted through the use of free radical polymerization initiators.
Gel coat compositions are typically made of unsaturated polyester resins, extenders and reactive monomers as diluents. Due to the reactive nature of these monomers, uncured gel coat compositions have a limited shelf-life or storage life, and the material will eventually begin to gel. As gel coat compositions are applied as liquid, surface gelation renders the compositions unusable. The shelf-life of the composition becomes shorter as storage temperature increases. Therefore, there is a need for gel coat compositions with extended-shelf life at various storage temperatures.